To implement lightweight structural concepts with a view to saving fuel, light metal components, for example, components made from aluminum or magnesium, are being used to an increasing extent in particular in the automotive industry. The components are generally cast, forged or extruded.
The said metals and their alloys form a passivation layer at the surface, and under standard climate conditions this layer provides good protection against corrosion. On the other hand, when exposed to media which promote corrosion, such as water and salt, these metals are subject to unacceptable levels of corrosive attack.
Numerous measures for coating light metals, in particular magnesium, have been developed to combat this problem. One standard process for producing a protection against corrosion on light metals consists of electrolytic coating, as described, for example, in EP 0 333 048. On the other hand, the drawback of this process resides in the complex and expensive retrospective coating of the components.
Accordingly, the object of the invention is to provide a process for preventing corrosion of light metal components which is less expensive than that used in the prior art.
The solution to the object comprises the features described below.